1. Field of the Invention
The present invention relates to a titania ultrathin film which is useful for ultraviolet shield coating of a window material which absorbs ultraviolet light having a wavelength of at most 300 nm with a high efficiency and others, and which is expected as a thin film for photoelectric conversion, a photochromic material, a photocatalyst thin film and a sensor, and a method for producing it.
2. Discussion of Background
A titania thin film is prepared conventionally by coating the surface of a substrate with a titania sol prepared by hydrolyzing a suitable titanium compound (such as titanium sulfate or titanium alkoxide) by means of e.g. spin coating. In such a case, the film thickness is at least sub-μm for the most part.
Further, colloidal particles dispersed in the sol have sizes of at least several nanometers and are in a substantially isotropic form, and the obtained thin film is a dense aggregate of spherical particles.